CN111217592A - Preparation method of tritium-proliferated ceramic pellets with high lithium content based on molten salt growth method - Google Patents
Preparation method of tritium-proliferated ceramic pellets with high lithium content based on molten salt growth method Download PDFInfo
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- 239000000919 ceramic Substances 0.000 title claims abstract description 114
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 94
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 41
- 150000003839 salts Chemical class 0.000 title claims abstract description 30
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- 239000008188 pellet Substances 0.000 title claims description 59
- 238000005245 sintering Methods 0.000 claims abstract description 44
- YZCKVEUIGOORGS-NJFSPNSNSA-N Tritium Chemical compound [3H] YZCKVEUIGOORGS-NJFSPNSNSA-N 0.000 claims abstract description 33
- 229910052722 tritium Inorganic materials 0.000 claims abstract description 33
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 59
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 46
- 239000000843 powder Substances 0.000 claims description 35
- 238000001035 drying Methods 0.000 claims description 34
- 239000002243 precursor Substances 0.000 claims description 34
- 235000015895 biscuits Nutrition 0.000 claims description 32
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 27
- 229910021485 fumed silica Inorganic materials 0.000 claims description 27
- 239000007788 liquid Substances 0.000 claims description 24
- 239000000243 solution Substances 0.000 claims description 24
- 229910052757 nitrogen Inorganic materials 0.000 claims description 23
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims description 22
- 239000002002 slurry Substances 0.000 claims description 22
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 20
- 239000008367 deionised water Substances 0.000 claims description 19
- 229910021641 deionized water Inorganic materials 0.000 claims description 19
- 229910003002 lithium salt Inorganic materials 0.000 claims description 19
- 159000000002 lithium salts Chemical class 0.000 claims description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 239000012266 salt solution Substances 0.000 claims description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
- 238000006243 chemical reaction Methods 0.000 claims description 16
- 239000011259 mixed solution Substances 0.000 claims description 16
- 239000000725 suspension Substances 0.000 claims description 16
- 239000007795 chemical reaction product Substances 0.000 claims description 14
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 14
- 239000002245 particle Substances 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 14
- 238000000227 grinding Methods 0.000 claims description 11
- 238000000498 ball milling Methods 0.000 claims description 10
- 230000035755 proliferation Effects 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 8
- 238000005303 weighing Methods 0.000 claims description 8
- 239000012046 mixed solvent Substances 0.000 claims description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 3
- 229910001416 lithium ion Inorganic materials 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- YTZVWGRNMGHDJE-UHFFFAOYSA-N tetralithium;silicate Chemical compound [Li+].[Li+].[Li+].[Li+].[O-][Si]([O-])([O-])[O-] YTZVWGRNMGHDJE-UHFFFAOYSA-N 0.000 abstract description 28
- 150000002641 lithium Chemical group 0.000 abstract description 8
- 230000008569 process Effects 0.000 abstract description 7
- 239000013078 crystal Substances 0.000 abstract description 5
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 abstract description 5
- 229910001947 lithium oxide Inorganic materials 0.000 abstract description 5
- 239000007787 solid Substances 0.000 abstract description 4
- 239000012535 impurity Substances 0.000 abstract description 3
- 238000005406 washing Methods 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 description 10
- 238000009395 breeding Methods 0.000 description 8
- 230000001488 breeding effect Effects 0.000 description 8
- 238000007605 air drying Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 238000007664 blowing Methods 0.000 description 5
- GLXDVVHUTZTUQK-UHFFFAOYSA-M lithium hydroxide monohydrate Substances [Li+].O.[OH-] GLXDVVHUTZTUQK-UHFFFAOYSA-M 0.000 description 5
- 239000011858 nanopowder Substances 0.000 description 5
- 238000007493 shaping process Methods 0.000 description 5
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 238000000280 densification Methods 0.000 description 4
- 230000004927 fusion Effects 0.000 description 4
- 230000005496 eutectics Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 230000008707 rearrangement Effects 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- PQVSTLUFSYVLTO-UHFFFAOYSA-N ethyl n-ethoxycarbonylcarbamate Chemical compound CCOC(=O)NC(=O)OCC PQVSTLUFSYVLTO-UHFFFAOYSA-N 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229940040692 lithium hydroxide monohydrate Drugs 0.000 description 1
- 238000009766 low-temperature sintering Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000004729 solvothermal method Methods 0.000 description 1
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Abstract
The invention discloses a preparation method of tritium-proliferated ceramic spheres with high lithium content based on a molten salt method. Lithium fused salt is decomposed to form lithium oxide in the sintering process and finally is dissolved in lithium orthosilicate crystal lattices in a solid mode, impurities are not introduced (compared with a conventional fused salt method, the procedure of washing out the fused salt is omitted), and the purpose of improving the lithium atom density can be achieved. The invention solves the problem that the preparation method of tritium propagation ceramic in the prior art is difficult to obtain density and strength at a lower temperature.
Description
Technical Field
The invention belongs to the technical field of tritium breeding materials, and particularly relates to a preparation method of tritium breeding ceramic pellets with high lithium content based on a molten salt growth method.
Background
As a key functional material in a fusion reactor cladding, the tritium breeder can react with neutrons to generate tritium, so that the fuel self-sustaining of the fusion reactor is realized. The lithium-based ceramic has the advantages of good chemical stability, easy tritium extraction, strong practical operability and the like, can be used at higher temperature, so that the lithium ceramic tritium breeder is more attractive than a liquid tritium breeder (with magnetohydrodynamic effect and corrosivity) from the safety of a fusion reactor. Among them, lithium orthosilicate ceramics is one of the first choice materials for solid tritium breeders because of its advantages of high lithium density, excellent tritium releasing performance, low neutron activation rate, etc.
Although a great deal of research work is carried out on the preparation and the performance of the lithium ceramic pellets at home and abroad, the contradiction between the densification and the grain growth of the lithium orthosilicate ceramic is difficult to solve because the microstructure of the lithium ceramic is extremely sensitive to the change of the sintering temperature. The ceramic crystal grain size is often larger due to the increase of the sintering temperature, so that the diffusion distance from the crystal grain to the crystal boundary is longer after tritium is generated, and the tritium release rate is reduced; and lithium is easy to sublimate under high-temperature sintering, so that the structural stability of the material is reduced, and normal tritium multiplication cannot be realized. However, lowering the sintering temperature will damage the sintered density of the ceramic, and further, the strength will be lowered. Therefore, the development of the lithium ceramic low-temperature sintering technology with the compactness and the strength meeting the requirements has important scientific significance and practical value.
In addition, in order to realize Tritium self-sustaining and fusion reactor steady-state operation, the Tritium breeding agent is required to have a higher Tritium breeding ratio (TBR >1), and the Tritium breeding ratio depends on the lithium atom density of the Tritium breeding agent (the larger the lithium atom density is, the larger the Tritium breeding ratio is). Despite the higher lithium content (23.33 wt.%) of lithium orthosilicate compared to other ternary lithium ceramics, the development of high lithium atom density ceramics remains an important direction of development for solid state tritium breeders. The addition of excessive Li element or lithium oxide (46.67 wt.%) is an effective way to increase the density of lithium atoms in the tritium breeder and compensate for lithium loss in the use of the material in the working condition environment.
Disclosure of Invention
The invention aims to provide a method for preparing tritium-proliferated ceramic pellets with high lithium content based on a molten salt method, which solves the problem that the preparation method of tritium-proliferated ceramic pellets in the prior art is difficult to obtain density and strength at a lower temperature.
The technical scheme adopted by the invention is that a preparation method of tritium-proliferated ceramic pellets with high lithium content based on a molten salt method is implemented according to the following steps:
step 1, preparing precursor powder with uniform particle size by adopting a mixed solvent thermal method;
and 3, preparing the lithium ceramic pellets.
The present invention is also characterized in that,
the step 1 is as follows:
step 1.1, adding lithium hydroxide into deionized water, and stirring to obtain a lithium hydroxide solution;
step 1.2, weighing fumed silica according to a lithium/silicon molar ratio of 4:1, adding the fumed silica into ethanol with the same volume as deionized water, and stirring to obtain a suspension of the fumed silica;
step 1.3, adding the suspension of the fumed silica obtained in the step 1.2 into the lithium hydroxide solution obtained in the step 1.1, stirring to obtain a mixed solution with the lithium ion concentration of 0.5-1.5 mol/L, transferring the mixed solution into a reaction kettle, reacting at 160-200 ℃ for at least 12 hours, drying a hydrothermal reaction product after the reaction is finished, and grinding the dried substance to obtain precursor powder.
And (3) drying the obtained hydrothermal reaction product in the step 1.3 by controlling the temperature of the hydrothermal reaction product to be 70-80 ℃ and preserving the heat for not less than 12 hours.
The step 2 is as follows:
step 2.1, adding lithium chloride and lithium nitrate in equal molar ratio into deionized water to obtain a lithium salt solution with the concentration of 5-20 wt.%;
step 2.2, ball-milling and mixing the precursor powder obtained in the step 1 and the lithium salt solution obtained in the step 2.1 to prepare slurry with the precursor powder concentration of 1.1-1.3 g/ml;
and 2.3, dropping the slurry obtained in the step 2.2 into liquid nitrogen to form small balls, and finally taking out the small balls from the liquid nitrogen and drying to obtain the lithium ceramic small ball biscuit.
In the step 2.3, the dropping speed of the slurry dropping into the liquid nitrogen is less than 20 drops/min.
And 2.3, taking the small balls out of the liquid nitrogen and drying the small balls, namely placing the small balls on filter paper, air-drying the small balls, transferring the small balls into a constant-temperature blast drying oven at 70-80 ℃, and preserving the heat for not less than 12 hours.
The step 3 is as follows:
and (3) sintering the biscuit of the lithium ceramic pellet obtained in the step (2), controlling the sintering temperature to be 700-800 ℃, setting the sintering time to be not less than 4h, and cooling to room temperature after sintering to obtain the lithium ceramic tritium proliferation pellet with high lithium content.
The invention has the beneficial effects that:
1. the invention adopts a mixed solvent thermal method to obtain precursor powder, has small powder particle size and less agglomeration, is beneficial to increasing the contact area between the powder particles and the lithium molten salt, and realizes quick and uniform sintering.
2. According to the invention, the wet forming process is improved, the ceramic slurry is prepared by adopting a lithium solution with a certain concentration, and the low-melting-point lithium eutectic salt is melted at 300-400 ℃ in the sintering process, so that the rearrangement of ceramic particles in a liquid phase is promoted, the contact area among the ceramic particles is favorably increased, and the rapid densification of the ceramic is realized.
3. According to the invention, decomposition products of different molten salts are analyzed, and lithium nitrate/lithium chloride with a certain molar ratio is selected as the molten salt, so that excessive impurity elements are not introduced to influence the physical and chemical properties of the tritium-proliferated ceramic, and the lithium molten salt decomposition products can improve the lithium atomic density of the ceramic, thereby compensating for lithium loss in a high-temperature service environment.
4. The invention effectively alleviates the contradiction between the grain size growth of the lithium orthosilicate ceramic (the sintering temperature needs to be reduced as far as possible) and the requirements of tritium propagation ceramic on high density and high strength (the sintering temperature needs to be increased as far as possible), and successfully prepares the lithium orthosilicate ceramic pellets with higher density and strength. In addition, the lithium orthosilicate ceramic prepared by the method has high lithium atom density and high purity, and is expected to be used as a next-generation advanced tritium breeding material.
Drawings
FIG. 1(a) is a schematic diagram of the preparation of a high lithium content tritium-proliferated ceramic based on a molten salt method;
FIG. 1(b) is a photograph of tritium-proliferated ceramic pellets with high lithium content prepared based on a molten salt method;
FIG. 2(a) is a cross-sectional SEM photograph of a lithium orthosilicate ceramic ball prepared in example 1;
FIG. 2(b) is an XRD spectrum of a lithium orthosilicate ceramic sphere prepared in example 1;
FIG. 3(a) is a cross-sectional SEM photograph of a lithium orthosilicate ceramic ball prepared in example 2;
FIG. 3(b) is an XRD spectrum of a lithium orthosilicate ceramic sphere prepared in example 2;
FIG. 4(a) is a cross-sectional SEM photograph of a lithium orthosilicate ceramic ball prepared in example 3;
FIG. 4(b) is the XRD pattern of the lithium orthosilicate ceramic spheres prepared in example 3.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
Considering that the lithium eutectic salt has a low melting point, the molten lithium salt preferentially forms a liquid phase during sintering, and further wets ceramic powder particles to promote rearrangement of the ceramic particles, thereby reducing the sintering temperature, increasing the pore removal rate, and rapidly achieving ceramic densification (fig. 1(a) is a schematic diagram). Meanwhile, lithium molten salt is decomposed to form lithium oxide in the sintering process and finally the lithium oxide is dissolved in lithium orthosilicate crystal lattices in a solid mode, so that impurities are not introduced (compared with the conventional molten salt method, the procedure of washing out the molten salt is omitted), and the purpose of improving the lithium atom density can be achieved.
Based on the concept of the invention, the main process flow of preparing the high-lithium-content lithium ceramic tritium proliferation pellets by the molten salt method comprises the steps of firstly preparing precursor powder with uniform particle size by a mixed solvothermal method, then preparing a lithium salt solution with a certain concentration, then carrying out ball milling to obtain slurry, obtaining a spherical ceramic biscuit by wet forming, and finally sintering to prepare the lithium orthosilicate ceramic pellets.
The invention relates to a preparation method of tritium-proliferated ceramic pellets with high lithium content based on a molten salt method, which is implemented according to the following steps:
step 1, preparing precursor powder with uniform particle size by adopting a mixed solvent thermal method, which comprises the following specific steps:
step 1.1, adding lithium hydroxide into deionized water, and stirring to obtain a lithium hydroxide solution;
step 1.2, weighing fumed silica according to a lithium/silicon molar ratio of 4:1, adding the fumed silica into ethanol with the same volume as deionized water, and stirring to obtain a suspension of the fumed silica;
step 1.3, adding the suspension of the fumed silica obtained in the step 1.2 into the lithium hydroxide solution obtained in the step 1.1, stirring to obtain a mixed solution with the lithium ion concentration of 0.5-1.5 mol/L, transferring the mixed solution into a reaction kettle, reacting at 160-200 ℃ for at least 12 hours, drying a hydrothermal reaction product after the reaction is finished, and grinding the dried substance to obtain precursor powder.
And (3) drying the obtained hydrothermal reaction product in the step 1.3 by controlling the temperature of the hydrothermal reaction product to be 70-80 ℃ and preserving the heat for not less than 12 hours.
step 2.1, adding lithium chloride and lithium nitrate in equal molar ratio into deionized water to obtain a lithium salt solution with the concentration of 5-20 wt.%;
step 2.2, ball-milling and mixing the precursor powder obtained in the step 1 and the lithium salt solution obtained in the step 2.1 to prepare slurry with the precursor powder concentration of 1.1-1.3 g/ml; the purpose of ball milling is to further refine and homogenize the powder particles, and to uniformly mix the powder particles with the lithium solution to realize uniform sintering;
and 2.3, dropping the slurry obtained in the step 2.2 into liquid nitrogen to form small balls, and finally taking out the small balls from the liquid nitrogen and drying to obtain the lithium ceramic small ball biscuit.
In step 2.3, in order to avoid the adhesion among the formed small balls, the dropping speed of the slurry dropping into the liquid nitrogen is less than 20 drops/min.
And 2.3, taking the small balls out of the liquid nitrogen and drying the small balls, namely placing the small balls on filter paper, air-drying the small balls, transferring the small balls into a constant-temperature blast drying oven at 70-80 ℃, and preserving the heat for not less than 12 hours.
The purpose of the step (2) is to obtain a spherical ceramic biscuit, a wet freezing and forming process is adopted, a lithium solution is used as a binder, liquid nitrogen is used as a refrigerant, and the slurry is formed into the spherical biscuit under the combined action of gravity and surface tension;
and (3) sintering the biscuit of the lithium ceramic pellet obtained in the step (2), controlling the sintering temperature to be 700-800 ℃, setting the sintering time to be not less than 4h, and cooling to room temperature after sintering to obtain the lithium ceramic tritium proliferation pellet with high lithium content.
The preparation method of the high-lithium-content lithium ceramic tritium proliferation pellet is different from the traditional sintering method in that: by utilizing the characteristic of low melting point of lithium nitrate/lithium chloride eutectic salt, ceramic powder particles are wetted by the molten lithium salt in the sintering process, so that the ceramic particles are promoted to be quickly rearranged, and the densification of the lithium orthosilicate ceramic is realized at a lower temperature; meanwhile, the lithium nitrate added in the step 2 is decomposed into lithium oxide through sintering, and can form a solid solution with lithium orthosilicate, so that the lithium atom density is improved. Finally, the lithium orthosilicate ceramic pellets with certain density and strength are prepared, the lithium atom density is more than or equal to 25.79 wt.%, the grain size distribution is 1-20 mu m, the density is more than or equal to 82% T.D., and the crushing strength exceeds 13.5N.
Example 1
(1) Preparation of precursor nano powder
6.712g of lithium hydroxide monohydrate (LiOH. H) were weighed2O) is added into 70ml of deionized water and stirred to obtain a lithium hydroxide solution; then 2.4g of fumed silica is weighed and added into 70ml of ethanol solution, and the mixture is stirred to obtain a suspension of the fumed silica; then, adding the suspension of the fumed silica into a lithium hydroxide solution, stirring to obtain a mixed solution, transferring the mixed solution into a reaction kettle, reacting for 12 hours at 180 ℃, after the reaction is finished, placing a hydrothermal reaction product into a 70 ℃ constant-temperature air-blast drying box for drying for 12 hours, and then grinding the dried substance to obtain precursor powder;
(2) shaping of biscuit of small ceramic balls
Adding lithium chloride and lithium nitrate in equal molar ratio into deionized water, and dissolving to obtain a lithium salt solution with the concentration of 5 wt.%; weighing the obtained precursor powder, adding the lithium salt solution, carrying out ball milling and mixing to prepare slurry with the concentration of the precursor powder being 1.2 g/ml; then, dropping the slurry into liquid nitrogen at a speed of less than 20 drops/min to form small balls, taking out the small balls from the liquid nitrogen, placing the small balls on filter paper for air drying, and then transferring the small balls into a constant-temperature air-blowing drying oven at 70 ℃ for drying for 12 hours to obtain spherical lithium ceramic biscuits;
(3) preparation of lithium orthosilicate ceramic pellets
And sintering the obtained spherical lithium ceramic biscuit in a sintering furnace at 750 ℃ for 4h, and cooling the sintered spherical lithium ceramic biscuit to room temperature along with the furnace after sintering to obtain the lithium ceramic tritium proliferation pellet with high lithium content.
The ceramic pellets produced in this example are shown in fig. 1(b) with a density of 82% t.d. and a lithium content of 27.25 wt.%; the SEM photograph of the cross section of the ceramic pellet is shown in FIG. 2(a), and it can be seen from FIG. 2(a) that the grain size is 1-3 μm and the average crushing strength is 13.5N; the XRD pattern of the ceramic pellet (measured after grinding the ceramic pellet) is shown in FIG. 2(b), and as can be seen from FIG. 2(b), the main component is lithium orthosilicate;
in conclusion, the lithium orthosilicate pellets prepared in the embodiment have good compactness and strength, and the obtained lithium orthosilicate pellets have small grain size and high lithium content.
Example 2
(1) Preparation of precursor nano powder
6.712g of monohydrate lithium hydroxide is weighed and added into 70ml of deionized water, and the mixture is stirred to obtain a lithium hydroxide solution; then 2.4g of fumed silica is weighed and added into 70ml of ethanol solution, and the mixture is stirred to obtain a suspension of the fumed silica; then, adding the suspension of the fumed silica into a lithium hydroxide solution, stirring to obtain a mixed solution, transferring the mixed solution into a reaction kettle, reacting for 24 hours at 160 ℃, after the reaction is finished, placing a hydrothermal reaction product into a 80 ℃ constant-temperature air-blast drying box for drying for 24 hours, and then grinding the dried substance to obtain precursor powder;
(2) shaping of biscuit of small ceramic balls
Adding lithium chloride and lithium nitrate in equal molar ratio into deionized water, and dissolving to obtain a lithium salt solution with the concentration of 10 wt.%; weighing the obtained precursor powder, adding the lithium salt solution, carrying out ball milling and mixing to prepare slurry with the concentration of the precursor powder being 1.1 g/ml; then, dropping the slurry into liquid nitrogen at a speed of less than 20 drops/min to form small balls, taking out the small balls from the liquid nitrogen, placing the small balls on filter paper for air drying, and then transferring the small balls into a constant-temperature air-blowing drying oven at 80 ℃ for drying for 24 hours to obtain spherical lithium ceramic biscuits;
(3) preparation of lithium orthosilicate ceramic pellets
And (3) sintering the spherical lithium ceramic biscuit obtained in the step (2) in a sintering furnace at 750 ℃ for 4h, and cooling the sintered spherical lithium ceramic biscuit to room temperature along with the furnace after sintering to obtain the lithium ceramic tritium proliferation pellet with high lithium content.
The ceramic pellets produced in this example had a density of 82% t.d. and a lithium content of 26.79 wt.%; the SEM photograph of the cross section of the ceramic pellet is shown in FIG. 3(a), and it can be seen from FIG. 3(a) that the grain size is 2-8 μm and the average crushing strength is about 16.9N; the XRD pattern of the ceramic pellet (measured after grinding the ceramic pellet) is shown in FIG. 3(b), and as can be seen from FIG. 3(b), the main component thereof is lithium orthosilicate.
Example 3
(1) Preparation of precursor nano powder
6.712g of monohydrate lithium hydroxide is weighed and added into 70ml of deionized water, and the mixture is stirred to obtain a lithium hydroxide solution; then 2.4g of fumed silica is weighed and added into 70ml of ethanol solution, and the mixture is stirred to obtain a suspension of the fumed silica; then, adding the suspension of the fumed silica into a lithium hydroxide solution, stirring to obtain a mixed solution, transferring the mixed solution into a reaction kettle, reacting for 12 hours at 200 ℃, after the reaction is finished, placing a hydrothermal reaction product into a 70 ℃ constant-temperature air-blast drying box for drying for 12 hours, and then grinding the dried substance to obtain precursor powder;
(2) shaping of biscuit of small ceramic balls
Adding lithium chloride and lithium nitrate in equal molar ratio into deionized water, and dissolving to obtain a lithium salt solution with the concentration of 20 wt.%; weighing the obtained precursor powder, adding the lithium salt solution, carrying out ball milling and mixing to prepare slurry with the concentration of the precursor powder being 1.3 g/ml; then, dropping the slurry into liquid nitrogen at a speed of less than 20 drops/min to form small balls, taking out the small balls from the liquid nitrogen, placing the small balls on filter paper for air drying, and then transferring the small balls into a constant-temperature air-blowing drying oven at 70 ℃ for drying for 24 hours to obtain spherical lithium ceramic biscuits;
(3) preparation of lithium orthosilicate ceramic pellets
And sintering the obtained spherical lithium ceramic biscuit in a sintering furnace at 750 ℃ for 4h, and cooling the sintered spherical lithium ceramic biscuit to room temperature along with the furnace after sintering to obtain the lithium ceramic tritium proliferation pellet with high lithium content.
The ceramic pellets produced in this example had a density of 83% t.d. and a lithium content of 25.79 wt.% (see analytical test report); the SEM photograph of the cross section of the ceramic pellet is shown in FIG. 4(a), and it can be seen from FIG. 4(a) that the grain size is 6-20 μm and the average crushing strength is about 22.5N; the XRD pattern of the ceramic pellet (measured after grinding the ceramic pellet) is shown in FIG. 4(b), and as can be seen from FIG. 4(b), the main component thereof is lithium orthosilicate.
Example 4
(1) Preparation of precursor nano powder
6.712g of monohydrate lithium hydroxide is weighed and added into 70ml of deionized water, and the mixture is stirred to obtain a lithium hydroxide solution; then 2.4g of fumed silica is weighed and added into 70ml of ethanol solution, and the mixture is stirred to obtain a suspension of the fumed silica; then, adding the suspension of the fumed silica into a lithium hydroxide solution, stirring to obtain a mixed solution, transferring the mixed solution into a reaction kettle, reacting for 12 hours at 160 ℃, after the reaction is finished, placing a hydrothermal reaction product into a 70 ℃ constant-temperature air-blast drying box for drying for 12 hours, and then grinding the dried product to obtain precursor powder;
(2) shaping of biscuit of small ceramic balls
Adding lithium chloride and lithium nitrate in equal molar ratio into deionized water, and dissolving to obtain a lithium salt solution with the concentration of 10 wt.%; weighing the obtained precursor powder, adding the lithium salt solution, carrying out ball milling and mixing to prepare slurry with the concentration of the precursor powder being 1.1 g/ml; then, dropping the slurry into liquid nitrogen at a speed of less than 20 drops/min to form small balls, taking out the small balls from the liquid nitrogen, placing the small balls on filter paper for air drying, and then transferring the small balls into a constant-temperature air-blowing drying oven at 70 ℃ for drying for 12 hours to obtain spherical lithium ceramic biscuits;
(3) preparation of lithium orthosilicate ceramic pellets
And sintering the obtained spherical lithium ceramic biscuit in a sintering furnace at 700 ℃ for 6h, and cooling the sintered spherical lithium ceramic biscuit to room temperature along with the furnace after sintering to obtain the lithium ceramic tritium proliferation pellet with high lithium content.
Example 5
(1) Preparation of precursor nano powder
6.712g of monohydrate lithium hydroxide is weighed and added into 70ml of deionized water, and the mixture is stirred to obtain a lithium hydroxide solution; then 2.4g of fumed silica is weighed and added into 70ml of ethanol solution, and the mixture is stirred to obtain a suspension of the fumed silica; then, adding the suspension of the fumed silica into a lithium hydroxide solution, stirring to obtain a mixed solution, transferring the mixed solution into a reaction kettle, reacting for 24 hours at 200 ℃, after the reaction is finished, placing a hydrothermal reaction product into a 80 ℃ constant-temperature air-blast drying box for drying for 24 hours, and then grinding the dried substance to obtain precursor powder;
(2) shaping of biscuit of small ceramic balls
Adding lithium chloride and lithium nitrate in equal molar ratio into deionized water, and dissolving to obtain a lithium salt solution with the concentration of 20 wt.%; weighing the obtained precursor powder, adding the lithium salt solution, and carrying out ball milling and mixing for 2h to prepare slurry with the concentration of the precursor powder being 1.3 g/ml; then, dropping the slurry into liquid nitrogen at a speed of less than 20 drops/min to form small balls, taking out the small balls from the liquid nitrogen, placing the small balls on filter paper for air drying, and then transferring the small balls into a constant-temperature air-blowing drying oven at 80 ℃ for drying for 24 hours to obtain spherical lithium ceramic biscuits;
(3) preparation of lithium orthosilicate ceramic pellets
And sintering the obtained spherical lithium ceramic biscuit in a sintering furnace at 800 ℃ for 6h, and cooling the sintered spherical lithium ceramic biscuit to room temperature along with the furnace after sintering to obtain the lithium ceramic tritium proliferation pellet with high lithium content.
Claims (7)
1. A preparation method of tritium-proliferated ceramic pellets with high lithium content based on a molten salt method is characterized by comprising the following steps:
step 1, preparing precursor powder with uniform particle size by adopting a mixed solvent thermal method;
step 2, preparing a ceramic pellet biscuit;
and 3, preparing the lithium ceramic pellets.
2. The method for preparing tritium-proliferated ceramic pellets with high lithium content based on the molten salt method as claimed in claim 1, wherein the step 1 is as follows:
step 1.1, adding lithium hydroxide into deionized water, and stirring to obtain a lithium hydroxide solution;
step 1.2, weighing fumed silica according to a lithium/silicon molar ratio of 4:1, adding the fumed silica into ethanol with the same volume as deionized water, and stirring to obtain a suspension of the fumed silica;
step 1.3, adding the suspension of the fumed silica obtained in the step 1.2 into the lithium hydroxide solution obtained in the step 1.1, stirring to obtain a mixed solution with the lithium ion concentration of 0.5-1.5 mol/L, transferring the mixed solution into a reaction kettle, reacting at 160-200 ℃ for at least 12 hours, drying a hydrothermal reaction product after the reaction is finished, and grinding the dried substance to obtain precursor powder.
3. The method for preparing tritium-proliferated ceramic pellets with high lithium content based on the molten salt method as claimed in claim 2, wherein the hydrothermal reaction product obtained in step 1.3 is dried by controlling the temperature of the hydrothermal reaction product to 70-80 ℃ and preserving the temperature for not less than 12 h.
4. The method for preparing tritium-proliferated ceramic pellets with high lithium content based on the molten salt method as claimed in claim 2, wherein the step 2 is as follows:
step 2.1, adding lithium chloride and lithium nitrate in equal molar ratio into deionized water to obtain a lithium salt solution with the concentration of 5-20 wt.%;
step 2.2, ball-milling and mixing the precursor powder obtained in the step 1 and the lithium salt solution obtained in the step 2.1 to prepare slurry with the precursor powder concentration of 1.1-1.3 g/ml;
and 2.3, dropping the slurry obtained in the step 2.2 into liquid nitrogen to form small balls, and finally taking out the small balls from the liquid nitrogen and drying to obtain the lithium ceramic small ball biscuit.
5. The method for preparing tritium-proliferated ceramic pellets with high lithium content based on the molten salt method as claimed in claim 4, wherein the dropping speed of the slurry dropped into liquid nitrogen in step 2.3 is less than 20 drops/min.
6. The method for preparing tritium-proliferated ceramic pellets with high lithium content based on the molten salt method as claimed in claim 4, wherein the manner of taking out the pellets from liquid nitrogen and drying in step 2.3 is that the pellets are placed on filter paper and air-dried, then transferred into a constant temperature blast drying oven at 70-80 ℃, and the temperature is kept for not less than 12 h.
7. The method for preparing tritium-proliferated ceramic pellets with high lithium content based on the molten salt method as claimed in claim 4, wherein the step 3 is as follows:
and (3) sintering the biscuit of the lithium ceramic pellet obtained in the step (2), controlling the sintering temperature to be 700-800 ℃, setting the sintering time to be not less than 4h, and cooling to room temperature after sintering to obtain the lithium ceramic tritium proliferation pellet with high lithium content.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101066883A (en) * | 2007-04-18 | 2007-11-07 | 中国工程物理研究院核物理与化学研究所 | Freeze forming prepn process of ternary lithium ceramic microphere |
| US20130078519A1 (en) * | 2010-06-28 | 2013-03-28 | National Institute Of Advanced Industrial Science And Technology | Production process for lithium-silicate-based compound |
| CN106630985A (en) * | 2016-12-16 | 2017-05-10 | 四川大学 | Nanostructured lithium orthosilicate ceramic spheres used for tritium propagation and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101066883A (en) * | 2007-04-18 | 2007-11-07 | 中国工程物理研究院核物理与化学研究所 | Freeze forming prepn process of ternary lithium ceramic microphere |
| US20130078519A1 (en) * | 2010-06-28 | 2013-03-28 | National Institute Of Advanced Industrial Science And Technology | Production process for lithium-silicate-based compound |
| CN106630985A (en) * | 2016-12-16 | 2017-05-10 | 四川大学 | Nanostructured lithium orthosilicate ceramic spheres used for tritium propagation and preparation method thereof |
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| GONG, YICHAO，ET AL: "A facile approach to fabricate Li4SiO4 ceramic pebbles as tritium breeding materials", 《MATERIALS LETTERS》 * |
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